turn the motor over by hand several times by hand to prime the oil pump and then start the car, see if the noise is no longer present.

if not, that link u sent about the accumulator sounds accurate but the noise doesnt sound like it would be related...i dunno

i am not sure what type of lifters this has but i would compress m113 ones by hand (it was tough)...the ones that were defective normally would click when compressed (like i could feel it if i took the lifter and put it in between my two fingers).....crank sensors go bad on benz all the time i highly doubt this model has a crank sensor tho....that will cause delayed start, hard start, etc...or fuel filter being clogged...i duno man its hard to say hope these ideas help

what is ur exact model i could ask a few people if u want

 

The engine is based on a 1986-1991 560SEL engine, but it's 10:1 pistons, lumpy cams, the 1981-1985 CIS style injection and ignition, some other stuff going on. (car started life as a 1985 380SE)

According to my service manual if you can push the lifter down by hand that means you have to replace it.

I do think the 560s had a crank sensor, but mine doesn't.

 

So, Abacus had the car for some other work and looked at this while they were at it. They said it's definitely a lifter not pressurizing as quickly as it should and they blame it on my low idle when cold. That answer doesn't really satisfy me because it does it longer the colder it is out, and it's only one valve (I have it narrowed down to one of the two valves for cylinder 7).

How bad is it to leave it like this? The lifter is only $50, but the tools I need to change it (MB proprietary valve spring compressor and go-no-go gauge) are $260. Will waiting until mid-January when I have the money hurt anything?

 

as the car genius stated.

 

Oh, yeah, I should explain. It's not a consistent tapping (I guess the engine just didn't like the 5w-40 I had in it, makes sense since it calls 15w-50 an "all-season oil" good down to +5F, and that's referring to non-synthetic oil), but a loud sound at start up. I.e. this isn't a shim issue, but a no pressure in the lifter issue.

In warm weather it's only a second or two, but now that it's cold it seems to last a while (maybe 10 seconds or so).

 

run some rislone through it...it may clean the lifter and make it work correctly again...

its called rislone..in a yellow bottle

 

As long as it's building pressure and working fine after a few seconds, there shouldn't be any undue wear. If it's seized and staying noisy, then it's not doing its job and will probably cause too much wear.

 

http://forum.miata.net/vb/showthread.php?t=221803

NA miata's are notorious for lifter noise, mine devolped it right around 130k, and it will go away if i dont run the miata hard, but as so as i take it to 7k in 1-3, i will devolp the noise, untill i drive normal for a couple off days